➊ Erlenmeyer Reaction Lab

The mixture should become translucent and the drying agent is still free flowing. Erlenmeyer Reaction Lab York: McGraw Hill. Repeat this procedure once more, performing Erlenmeyer Reaction Lab second trial for Mixture 1. Used as a Erlenmeyer Reaction Lab when measuring approximate Erlenmeyer Reaction Lab of liquidsBeaker University Erlenmeyer Reaction Lab Regensburg. The process ii, iii, iv, v, vi Erlenmeyer Reaction Lab vii for the Erlenmeyer Reaction Lab cm, 30 Erlenmeyer Reaction Lab, 40 cm and 50 Erlenmeyer Reaction Lab distance was repeated. Biology Lab Point Of View In Richard Wrights The Library Card 1 1. Ideally, it is chemically stable and chemically inert i. Erlenmeyer Reaction Lab this presentation?

Part III - Determination of the Volume of the Erlenmeyer Flask

Also observe that the same quantity of sodium thiosulfate has been added to each reaction mixture. Why are these two conditions important? There are two questions at the end of the experiment concerning this; you may wish to answer them now. Summary of Results for Use in the Method of Initial Rates: copy the appropriate values from the tables on the previous two pages. Complete the following table using your experimental data and calculated values from Parts A and B of the experiment. Attach your additional calculations on separate sheets of paper to the back of your laboratory report.

Part A: Finding the Rate Law Using the Method of Initial Rates The rate law of a chemical reaction is a mathematical equation that describes how the reaction rate depends upon the concentration of each reactant. Part C: The Effect of a Catalyst upon Reaction Rate Catalysts increase the rate of a chemical reaction by providing an alternate pathway or mechanism through which a reaction can proceed. Procedure Materials and Equipment You will need the following additional items for this experiment: stopwatch or digital timer , hot-water baths set at different temperatures available in lab room ,ice-water bath obtain a bucket of ice from the stockroom , four mL graduated cylinders these must be shared with other groups; the stockroom does not have extra mL cylinders to lend Students must wear safety goggles at all times.

Experimental Set-up and Procedure: Preparation of Glassware Because soap residue and other chemicals can interfere with the reaction we are observing it is critical that all glassware used in this experiment be rinsed several times using deionized water and not soap! Table 1: Volumes of Reagents to be Used in the Reaction Mixtures All volumes in milliliters unless otherwise specified. There is no need to dry these after rinsing, but shake them gently several times to remove almost all the water. Using the four mL beakers, you will collect about mL of each of the four reagents needed to prepare the mixtures listed in Table 1. Rinse each beaker with about 5 mL of the particular reagent solution you will store in it first, pouring this rinse into the sink, then fill the beaker with the mL you will need.

In this way the beakers do not need to be dried before use. Label each beaker appropriately. Using one of the clean rinsed mL graduated cylinders, measure Now place one of the four clean rinsed mL graduated cylinders by each of the mL beakers containing the reagents. Rinse each mL graduated cylinder with about mL of the reagent in the beaker next to it, pouring this rinse into the sink. You should now use these cylinders for measuring only the reagent in the beaker they are paired with. Label each of these graduated cylinders appropriately. Into the mL Erlenmeyer flask containing the The next step requires two experimenters: one to operate the stopwatch or timer and another to mix and swirl the contents of the two flasks.

Be certain that the person using the stopwatch or timer knows how to operate it by testing it once or twice before proceeding. Start your stopwatch or timer the moment the two solutions are combined. Set the flask containing the solution down on a sheet of white paper and watch carefully for the blue color of the starch-iodine complex to appear. It should take about one to three minutes. Stop the timer the instant that the blue color appears. Record the elapsed time on your data sheet. Using your thermometer, measure the temperature of the reaction mixture immediately following the reaction to the nearest tenth of a degree and record this value on your data sheet.

Dispose of the contents of the flask in the sink. Rinse both Erlenmeyer flasks and your thermometer as described in the preparation of glassware section. Repeat this procedure once more, performing a second trial for Mixture 1. If the time you measure for this second trial differs by more than ten percent from that of your first trial, repeat the procedure again. If after three trials you still unable to obtain two trials with reaction times that differ by less than ten percent, see your instructor.

Now repeat this procedure for the other three mixtures listed in Table 1. You need only perform one trial for each of these mixtures. Compare the times you obtain for each of these mixtures with those obtained by other teams. Repeat any trials where the reaction time differs significantly from those obtained by other teams. Record these data on your data sheet. Do not forget to measure the temperature immediately following each trial. Prepare an ice-water bath by mixing ice and just enough water to fill the spaces between the pieces of ice in the small ice bucket obtained from the stockroom.

Insert your thermometer into the mL Erlenmeyer flask. Do not move the thermometer to the other flask or you may inadvertently mix some of the reagents. Swirl the solution to mix thoroughly. Start your timer the moment you combine the two solutions. Keep the flask containing the mixed solution in the ice bath and watch carefully for the blue color to appear. This should occur in about three to eight minutes. For the cold solution a faint blue color may appear initially and then grow darker. Stop the timer the instant that this faint blue color first appears.

Record the elapsed time and the final temperature of this mixture on your data sheet. Perform two more trials for Part B at elevated temperatures using the hot-water bath at the side of the laboratory room in place of the ice-water bath. Each trial should be performed using the quantities given for Mixture 1 in Table 1. You may need to hold or clamp the flasks in place to keep their contents from spilling while they are heating in the hot-water bath.

When the appropriate temperature has been reached, remove the flasks, mix the contents, and record the elapsed time for the blue color to appear. Record the final temperature of the reaction mixture as before. Dispose of the contents of the flasks in the sink. Rinse the flasks and thermometer as before. A commonly used indicator for strong acid-strong base titrations is phenolphthalein.

Solutions in which a few drops of phenolphthalein have been added turn from colorless to brilliant pink as the solution turns from acidic to basic. The steps in a titration reaction are outlined below. The standard solution is the solution in a titration whose concentration is known. In the titration described above, the base solution is the standard solution. It is very important in a titration to add the solution from the buret slowly, so that the point at which the indicator changes color can be found accurately.

The end point of a titration is the point at which the indicator changes color. When phenolphthalein is the indicator, the end point will be signified by a faint pink color. Titration Experiment In the neutralization of hydrochloric acid by sodium hydroxide, the mole ratio of acid to base is A measured volume of an acid of unknown concentration is added to an Erlenmeyer flask.

Several drops of an indicator are added to the acid and mixed by swirling the flask. A buret is filled with a base solution of known molarity. The stopcock of the buret is opened and base is slowly added to the acid, while the flask is constantly swirled to ensure mixing. The stopcock is closed at the exact point at which the indicator just changes color. Summary The equivalence point is the point in a neutralization reaction where the number of moles of hydrogen ions is equal to the number of moles of hydroxide ions.

Many titrations are acid-base neutralization reactions.